A-weighted sound power level of electric vehicles in accelerating and decelerating conditions

To evaluate the exterior noise reduction effects of electric vehicles (EVs) and hybrid electric vehicles (HEVs) under non-steady speed conditions, i.e., accelerating or decelerating running conditions, measurements of A-weighted sound power levels were conducted. This paper reports the results of a reanalysis using the data measured at the same test site. The results are shown as regression models of the sound power level depending on the vehicle speed. For internal combustion engine vehicles (ICEVs), there was a strong tendency for LWA to increase when the acceleration was greater than 1.0 m/s2. For EVs, when the acceleration is less than 2.0 m/s2, which is considered the typical acceleration in general urban driving, it can be considered equivalent to the LWA under steady-speed condition. During deceleration, there was no significant difference from steady-speed condition for either vehicle type. These differences were examined in terms of single-event sound exposure levels. In a case study that included stopping and going at a traffic signal, the difference in LEA was shown to be 3.0 dB.